1. Field of the Invention
The present invention provides a color plasma display panel, and more particularly, to a color plasma display panel that can adjust the covering area of fluorescence layer to increase the color temperature.
2. Description of the Prior Art
Color plasma display panels (PDP) is teamed up with several hundred thousand display units in permutations and combinations which is several hundred micrometers in size, the light source comes from applying a voltage on a discharging gas in order to produce ultraviolet rays. When the ultraviolet rays incident on different fluorescent layer, the fluorescent layers will emit three colors: red, green and blue. Generally speaking, the material of the fluorescent layer determines the color emitted from the fluorescent layer. When the fluorescent material contains (Y,Gd)BO3 and Eu, a red fluorescent ray will be produced; when the fluorescent material contains ZnSO4 and Mn, a green fluorescent ray will be produced; when the fluorescent material contains BaMgAl14O23 and Eu, a blue fluorescent ray will be produced.
However, the fluorescent material becomes degraded because of heat, therefore, the quality of the blue fluorescent ray is poor. The present technique for improving the luminescent quality of color plasma display panel is to enlarge the discharge space of blue fluorescent ray in order to increase the covering area of the fluorescent material. In the meanwhile, the ratio of red fluorescent ray, blue fluorescent ray, and blue fluorescent ray is adjusted in order to increase the color temperature of PDP from 7000xc2x0 K. to 11000xc2x0 K.
Referring to FIG. 1, FIG. 1 is a schematic diagram of color plasma display panel 10 in according to the prior art. The prior art color display panel 10 comprises a first substrate 12, a second substrate 14 parallel to the first substrate 12, a discharge gas (not shown) that fills the space between the first substrate 12 and the second substrate 14, a plurality of first electrodes 18, a plurality of second electrodes 20, and a plurality of addressing electrodes 22. Each of the first electrodes 18 and each of the second electrodes 20 is positioned on the first substrate 12 in parallel. Each of the address electrodes 22 are positioned on the second substrate 14 and are orthogonal to the first electrodes 18 and the second electrodes 20.
Each of the first electrodes 18 and the second electrodes 20 respectively comprises a sustaining electrode 181, 201,and an auxiliary electrode 182, 202. The sustaining electrode 181, 201 is usually made of indium tin oxide (ITO), and the auxiliary electrode 182, 202 is usually made of a Chrome/Copper/Chrome (Cr/Cu/Cr) metal alloy. The sustaining electrode 181, 201 has high resistance, but is transparent to visible light. The auxiliary electrode 182, 202 has a good conductivity and is used to increase the conductivity of the first electrode 18 and second electrode 20.
The plasma display panel 10 further includes a dielectric layer 24 that covers the surfaces of the first substrate 12. A protective layer 26 then covers the dielectric layer 24. A plurality of barrier ribs 28 are positioned in parallel on the second substrate 14 to define a plurality of discharge spaces 30 of strip shape. Each addressing electrode 22 is positioned between two adjacent barrier ribs. A fluorescent layer 32 coats on the bottom of each discharge spaces 30 and the side wall of the barrier rib 28 within each discharge space 30 in order to produce the red, green or blue rays. Each of the discharge space 30 comprises a plurality of display unit 34, and all of the display units 34 are arranged between the first substrate 12 and the second substrate 14.
In addition, all of the stripy shaped discharge space 30 consists of a plurality of discharge space set, each discharge space set includes a red discharge space 30R coated with red fluorescent layer 32R, a green discharge space 30G coated with green fluorescent layer 32G, and a blue discharge space 30B coated with blue fluorescent layer 32B. Therefore, a plurality of red display units 34R are formed within the red discharge space 30R, a plurality of green display units 34G are formed within the green discharge space 30G, a plurality of blue display units 34B are formed within the blue discharge space 30B. A red display unit 34R, a green display unit 34G, and a blue display unit 34B is defined as a pixel.
As mentioned above, in order to improve the quality of the blue fluorescent light, the width of the blue discharge space 30B will be enlarged. The width of the red discharge space 30R is designed as the narrowest one, the width of the green discharge space 30G is designed as the medium one, and the width of the blue discharge space 30B is designed as the largest one. The width of the green discharge space is about 1.2 times of the width of the red discharge space 30R, and the width of the blue discharge space 30B is about 1.6 times of the width of the red discharge space 30R in according to the prior art. Therefore, the space of the red display unit 34R is the smallest one, the space of the blue display unit 34B is the largest one in order to adjust the ratio of red, green, and blue fluorescent light from plasma display panel 10. Therefore, the surface area of the blue fluorescent layer 32B coated in blue display unit 34B will be the largest, the surface area of the red fluorescent layer 32R coated in red display unit 34R will be the smallest. Therefore, when the discharge gases are discharged to produce visible lights, the amount of blue light will be larger. Therefore, the red, green, and blue lights are mixed subtly to reach the white balance state, and the color temperature of color plasma display panel 10 is. increased to around 11000xc2x0 K.
However, the resolution of the plasma display panel is continuous increased and the widths of all discharge spaces begin to shrink. Since the ratio of the widths of the discharge spaces 30 is designed as a fixed proportion, the width of the red discharge space 30R is then very small. Hence, it becomes difficult to manufacture the barrier rib 28 and the red fluorescent layer 32R. The alignment of the first substrate 12 and the second substrate 14 becomes difficult, too. In addition, the width of the red discharge space 30R is too narrow so the cross-talk problem of the discharge gas is increased to cause interferences, and further influence the electrical performance of the color plasma display panel 10.
It is an object of the present invention to provide a color plasma display panel having a higher color temperature and a higher covering area of the fluorescent layer.
In accordance with the preferred embodiment of the present invention, the plasma display panel comprises a rear plate having a rear plate surface thereon, a front plate parallel to and spaced apart from the rear plate forms a space between the front plate and the rear plate. A first, a second, and a third barrier ribs are positioned on the rear plate, these ribs are formed in parallel and spaced apart from each other by a predetermined distance. The space between the first barrier rib and the second barrier ribs is defined as a first discharge space, and the space between the second and the third barrier ribs is defined as a second discharge space. The plasma display panel further comprises a first bottom rib positioned on a first region of the rear plate surface in the first discharge space, and a second bottom rib positioned on a second region of the rear plate surface in the second discharge space. The first bottom rib has a first thickness and the second bottom rib has a second thickness. A first fluorescent layer is coated on the surface of the first bottom rib and the sidewall surface of the barrier rib surrounding the first discharge space. A second fluorescent layer is coated on the surface of the second bottom rib and the side wall surface of the barrier rib surrounding the second discharge space. The first fluorescent layer has a first surface area and the second fluorescent layer has a second surface area. The second thickness of the second bottom rib is larger than the first thickness of the first bottom rib, so that the first surface area of the first fluorescent layer in the first discharge space is larger than the second surface area of the second fluorescent layer in the second discharge space.
In addition, the plasma display panel further comprises a fourth barrier rib parallel to the third barrier rib and spaced apart from the third rib the predetermined distance on the rear plate. The space between the fourth barrier rib and the third barrier rib is defined as a third discharge space. A third bottom rib is positioned on a third region of the rear plate surface in the third discharge space, and the third bottom rib has a third thickness. A third fluorescent layer is coated on the surface of the third bottom rib and the side wall surface of the barrier rib surrounding the third discharge space. The third fluorescent layer has a third surface area. The third thickness of the third bottom rib is larger than the first thickness of the first bottom rib so that the third surface area of the third fluorescent layer in the third discharge space is smaller than the first surface area of the first fluorescent layer in the first discharge space.
In another preferred embodiment of the present invention, the plasma display panel comprises a rear plate having a rear plate surface thereon, and a front plate parallel to and spaced apart from the rear plate for forming a space between the rear plate and the front plate. A plurality of barrier ribs are positioned within the space, the ribs are formed in parallel and spaced apart from each other by a predetermined distance so as to define a plurality of discharge space groups therebetween. Each group comprises a first, a second, and a third discharge space. These spaces have a substantially equal volume. The plasma display panel further includes a first, a second, and a third fluorescent layer. The first fluorescent layer is coated on a first region of the rear plate surface in the first discharge space and a first sidewall surface of the rib surrounding the first discharge space. The second fluorescent layer is coated on a second region of the rear plate surface in the second discharge space and a second sidewall surface of the rib surrounding the second discharge space. The third fluorescent layer is coated on a third region of the rear plate surface in the third discharge space and a third sidewall surface of the rib surrounding the third discharge space. The first fluorescent layer has a first thickness, the second fluorescent layer has a second thickness, and the third fluorescent layer has a third thickness. The third thickness of the third fluorescent layer coated in the third discharge space is the largest, the first thickness of the first fluorescent layer coated in the first discharge space is the smallest, so that the surface area of the first fluorescent layer coated on the side wall surface of the barrier rib surrounding the first discharge space is larger than the surface area of the third fluorescent layer coated on the barrier rib surrounding the third discharge space.
In the present invention, the distances between the surfaces of the bottom ribs and the front plate are different or the thickness of each fluorescent layers are different so that the surface area of the fluorescent layer coated on each discharge space will be different. Therefore, the ratio of the three nature colors will be changed to reach a better white balance state. The color temperature of the plasma display panel is also increased to about 11000xc2x0 K., the problems cause by the misalignment of the plates and the cross talk phenomenon of the discharge gas can be avoided at the same time.